SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '284b3a76ce562a49ad211f60e7b736035a7084ac464037e94267c578715413d2' 
  AND token = 'pUiZnfsqoZbhnk/TzYWK/RNE5ZhfAyx+p9swErgH3LQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00016

JSON explain

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