SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '623540137b82d7537f6bed44f2146525bb12136c6a6718962a06a2f9f480a328' 
  AND token = 'lcDpHOQIbCgEkwKYv+oQHkEv6+eOPWX3jfBkhA0brIQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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