SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f87a271670115bf38486b627e75229a08a39d9203d482623a3a387ff35aa0a10' 
  AND token = 'uvhXGM9us2Bo9I4j9ao9rIg0mYRCJNlDMMuTEp+dM2Q=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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