SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '29f1ea3f63b535233a2a2b4d7242f8a1999c30ae9a42208bb5091738692acd56' 
  AND token = 'SJTkNEPKgL2Z1rVdLEHPYMsIptxQK6hQ2LwzxGon3Xc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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