SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5e95e0e62f4a416afd209d20d7e89f3da521409524aeae60779e462a8f8ccfc4' 
  AND token = '9AzY/PQuz0CxtPqS7dEk+noK3kUyAfV5K0YczBtv+Vc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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