SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '39f480ea772aa1063876bb45e282f011a6de749341e426c9607d21a92de57162' 
  AND token = 'tS+eCGWTMVJbrpi6IEcvQ1JfcxwueMMjbeVo40kjQtw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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