SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e20e6a45feb2c5c012efb7589823a4e1ddd13d7d1c5bc2803dfafe72e1b28665' 
  AND token = 'RvnoVjWGaCOrbup517nha3HLcsE4Ssd4UPhJjVN16kY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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