SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '268011ed96864254b9b634c8cf633a4adf98b1880480337ddd6a0d2595144a59' 
  AND token = 'qaVExkNIHMDhCDf9Lp836TE00+gfQWV7+NIQcnSyDmg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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