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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '15f40ceb21f934f6fa3b83177a014ec5cf58f3f22b2b52280f7944f5c1fd1b0d' 
  AND token = '3TBuc87EO3fNkTBnVxmrlMHfwXDJPcZKlXw58HMmHKg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}