SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '37b9d73f37ac222572b489ee74eea16ae8d1fac5cece21cb1fe0c72672fe6451' 
  AND token = 'F2JjWDstWM6dRCInstYskeU4EZWWmniMg0ouRVTCWXw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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