SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '99e933999ed25035db140540be8d52b3a29e55edb10adf9e1ab501be3c808f4d' 
  AND token = '6nS7OVPfQ2XRjjHOdXfZ2orPLCIK27AWLAO8KvjxTDw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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