SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '83ef97027d9b8522bccd76dc922564eb68ceea7000d7f58e808ff4b8fd994f3d' 
  AND token = 'jJsMCmHpjzf00egY+r1CZ4uHAptcwsAAL57oZFh5GjY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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