SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8f8420915813b354878561a1558d5ab4758548fadd8ab6c114278698d097f234' 
  AND token = 'IiIijSRsfDg9fyU2nwifyXTyxhq/c7EYMSAoRq/JP7s=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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