SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3adaa3400651845c3e542eb0a120299d1a8436ffaf3053d01841ecad1fe61223' 
  AND token = 'P3abxwFoDc/BNUZCsGUW2o5tCvy8ll3jmL9oCPXHwQ4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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