SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = '3528b93eb74f6af7f202ac4d737965ed69891a1402f997b12495b6c8124d7e08' 
  AND token = 'uMQfJbGLUNJISgddqze/mWe0+FKQciWvYwHMdsHKhI0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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