SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd75769b7d1b8d18dfb80398a5c6f5008450e1211f2ec178617b0e89fac40b3cd' 
  AND token = 'r86X+0l7/9LKBlk7nNJZurzAtS5Rh11414LPyRoVYlo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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