SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6a9a4e9647932eeb72192dd0c51e064bdc79ccbc3c45e15168806b669b66830f' 
  AND token = 'JLrkUCWgv0/PVKZt4/ECP2TlsjXqlVaD/oP8uDZh5LI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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