SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3c7e19faf88a40d7a786fceaf96633a0d83b0e58a18f4ab7551a7a964a4ae758' 
  AND token = 'UP0gRHViO6/PbaJpfixIAGed6baFZiyqx452hLVfwN0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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