SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '71efc7581503cdcbf7433418f5a35faea8e5344387a2afe4ec85fb1ad6316d51' 
  AND token = 'OgmvZz8Z9oo09GPwP1TlCmGqFtlAxgIwSSe4vVFDJmM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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