SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '24ca521c0babf2d12fc757f938af4b2a9f6a5279d406ead3308d881230010b84' 
  AND token = 'TCU6ggwzq5n45jj4ltcasZbBEYAEQD+PPFIUc/JlhQQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00016

JSON explain

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