SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '25f0645e9330ad3b3464e71bac017c0824cddfebd27a9a183d805a45daece3d9' 
  AND token = '4hhTbvge67FiAdmodbJ9vZNTWcMtlAYeGjabaWmUbHs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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