SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6fe29b1bc128c07c86685724366741baf4d07603f114324bc93e386d6217cb37' 
  AND token = 'n1qz2rFDVlVB6sgHhYUqIeR/UxXy5aQvz2in3XbqjSc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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