SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c6ad00dc62530504542d0c1ac8c3bc438e11e8118cff837eb054aaa788fb83cd' 
  AND token = '5C/TrEFCtUmazXw4HxZOxiWUsg0USOANkni04KyMIig=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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