SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '815654569b9a597a63739ba28edee78c29be1ad329d1723fdad1d0b64aae49d5' 
  AND token = 'DjsfP6kgFBDRKQni5nnjCBlbUCnSS0/a6Nhc9k6ZraQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}