SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f5f95251abf9761651bca75c72f4d185c284d0fe4d93a9652cdacfeafe2abff6' 
  AND token = 'fXHHjRdDA4UdYQ+RdB5pnbzPFcJPlcSqtvum8kvD1BQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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