SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f270767c7d4308bd024cb2c5e577eae096cdf45d01da4a095dc4c434e982fec5' 
  AND token = 'RIf6w3ZoZiI7yR3ZebGFYpuQgkb4KjEfF/v/hq9wQ0s=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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