SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f1cec5050ca4516c163df9e1c7937980701ef8843aed3d9ea50e1a706e03c703' 
  AND token = 'hYqhwBa/ib6u2lfR1VTZXRvPKoLU/jCd5JWgSKWHh0Y=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00047

JSON explain

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