SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f2fb3b3073fe656820122277109049acfdc484b5e7740ec268b3724e0877d362' 
  AND token = 'kukLNNG8GKQRKx22D2omtE9u5SdM3xmzyOs7YyRT/CY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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