SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a6414a653c72e8a3e036daa7a67bf61a1268dbb1ccee28e4215163ea68e1a8ba' 
  AND token = 'T4LAXSpnXlMGGPUtAqREaM/CcpvsvTTY2vHjSQJWzEI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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