SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '74a425ec02261394fb691ab9013b61937addd8a3f0c46d1084a7507c923aed35' 
  AND token = 'YaUgEnYKtU51gqzp4FUpaQV/1FnhsiV5iEroPZnk4T0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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