SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '18ef8395723d1d80737e9f061f24e40078c6a4417451523931bb8115bca07b53' 
  AND token = 'tTWOvAdAKJ8xKHWKPFBWP6FEIcHRGBNcrGEok481qo4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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