SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f7157c9ec48d5ee5172e2f6df6544e56e341ed093d35bbc8f6c5485684bb832c' 
  AND token = 'UPv4wPDQXSMNgHLRXpG7mVqpOWIt7gpQbp/qsCIcbcU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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