SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b54368566fa257fe316c33cbc8da99d4d429c2d20e3f21d3f6137b667ee15620' 
  AND token = 'jeVv6U3VcS+wfC5B+Yu0BRGdrFsg7F8Gnzz3Gg/G1BQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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