SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6e4972f3af56a0701fc161c1b0abc250c3f71ea88524e2b21ab7804ee42b2818' 
  AND token = 'XbPf/rcf0C06JfhrQHowk3EOfoLjxWVPk4yueeMljRQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00059

JSON explain

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