SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '28f5db6b61a616a526b454f936c97a6d8d7b0f1f08842c7b84d3115278718795' 
  AND token = 'kFGZbMLxgz0NN4atpS1WV0UG7STDEFYcjRMuNmYazK4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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