SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '390e22db20fe42d06a23c96416d0d8e9b6bddef7c5830994af0c4dec92020938' 
  AND token = 'wYaUWLG7zEQbL0OcmNPJlxybLYlcbHKWGzUCnf2g0eM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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