SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f15becee423b51d882b3056e1c8f50bcc141ec7367798c1e5e25133f20a07369' 
  AND token = 'EIstn4yomMzG4jEpXCHPr5N/BE9kJcXYLM+x23SdNBU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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