SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3c49d19547ce585de29c18b9a22bd57e8940284114eb140f0755ea07670a382a' 
  AND token = 'mWxvkHcbzg6dT16dxxajcDS/itbvVKeMPLaeZtc+crk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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