SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '327be0b9f678a04dfa267f2370af3272acc0a28afb09b9f648d6637d989e5e38' 
  AND token = '2QDZCB0gKuW2dwoRQPwcYdsV58uPy6Yqb/Vy+Rg0/sY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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