SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1a7a307a62752c837bf1864fec957bb76a2242448a35f3f148209eeb808c93cf' 
  AND token = '7seNDJoPIzxYke4refP1tA7Z77Rj0MFHOMsJZzf9XwY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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