SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '20a158aac22f798979d9d9d2510ebc3f4809fe1d84cf822c9b3e5f6bc150f815' 
  AND token = 'mqe/SDNEXhIdvEpURDvYDaLrPxdDazVaYx79WFdsrsk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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