SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'adc4f0c1f8dd2b39d8e11a903de5f11ca8eb61d2fe972f4ef2e71838dd7f42c5' 
  AND token = 'XBCM4i9VmTKsY+PkvCJk/KaP4JAvbKzFXVIVFUBeyAw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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