SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ea703235c07e1737ad23bd04b730c6309f4f1d123840ea1f273ac67164627b39' 
  AND token = 'OpL0rLJHP50XQYkmcTALQwZvjrhCHRv27Hn/CwXQi/I=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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