SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '90bbe186fe998745348dc60b628d2d1c8f2d42037dfeffb386af2115a69bd62f' 
  AND token = '8QlRIuXZpjPJ/F8JgnHWhoszSmo5ssz2ufG+bNJxUik=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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