SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '667cf382233dc8bad71c0107a397cf41fd9e3ed39b9447650c1e19747b30d348' 
  AND token = 'DqoA/m8qwwCzYv2MXdQer4QluJT7nnazy2NYDvlglRM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00054

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}