SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '78a53c5b802eb1e8a065b467a7bd5d1dcb09fc356f147ddd105433697b3ff369' 
  AND token = 'ScfRjJoEYgztdiLlw60MxEfviRFd1QW/Vitr4VBJp8Q=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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