SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd8fbcadc5f3c199cb790e7b234677a5a23eb2a560f5fe1092da98a355c8846cb' 
  AND token = 'dW7BtabLEcQ9a/Y2kyQecP42OAmb5b5lVfYhk/Ayl4k=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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