SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '73fdb8b51c909290f882d193da2ea7c295399aff4033235fac5cd003cfe270a5' 
  AND token = 'XoChHF2LQBRAc2tTwPlbWA6fESef7UFKT+v3XkSoUXs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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