SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f522415fc487ddb038a5b9668cde582e52fca65a904de2006f4539ed4f91672d' 
  AND token = 'uhzu1ij46gBRzRJD+H4kywkENu6v0ht7YlOEr6BGvYI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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