SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4b8e6783391d406624479b57caf36c005291cfe949631411acf0a0c73bce0838' 
  AND token = 'zpJ2U86IIeSQ2LGOZ7GYGzMoCsE1qOMGigVYk4BQEmQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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