SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fa54ed51612396ccdc1f12c0d1660f61afde8a00a8bf4fb1409c31600be77259' 
  AND token = 'iLNEGpHMMT96thiqpVGlPXgK3wuyvAZK7wUnXTtCJgY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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