SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8fd13d5b231e29379710a5a7d9def8c9e9cab7275f0203b28e46d07acd960279' 
  AND token = '7q2yYHbmTwOUM+LrAHXz37g/XiM0vP0NQArVCamicbA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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