SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7451fbf62653e9eb763607775f2071edd105900a4869ffa1720b08573d9a5764' 
  AND token = '+yuE9v+izfaNbwTahluDfzTQAv/cfhEPTSHbgDPDRPY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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