SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b9a973743bd9a236f0aaf151b9902ce3978b857305d8e1342867295543913e21' 
  AND token = 'VWWUOH4R9Tjmnp9irqYw+sWvJRMGp13jhct+8YwEKHc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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