SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'dd4867c8e645eea35f9847812f5e3181ccdffbeb2c3c6657f664527d8c5e0920' 
  AND token = 'Z/Z7zUBGK4ejZjLM/2jbfNryAG3XhUjrfw6sYfqo1Bg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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