SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '549c35ceaf01b37c3e267696eb9db237efdcef0b3259942334ee509d37981741' 
  AND token = 'w6qJhkQKgDVvw/Xlq0m5jp23TKLsLdL5vuTXm+T4jE4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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