SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '939c86f1ca7601d603ea810ec4fe0fe8e27d6c5fdf743b9fb79d3b12aae77fad' 
  AND token = 'YFCcY62zxScPv5ZgWVzwMhWOINwTRRtEC65AnlWqZLQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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