SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b6c0ed26449cd86869914bdcddde7d647cbbd7a990e510c15249b04c67fe1bd6' 
  AND token = 'YKvlyWO8UoV5Hwhi3SHoH0qZxEIjB8A4NPvzwPz/8cA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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