SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f9a524c1e695600874f3d318e54dfacb16d15a4f3ae281f143f062bda9b48276' 
  AND token = 'gqn9vjTDR9sFpBDxvJazCVmsJRcPQZTtZ0efNZzATEA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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