SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3f910101f234cac0809085b874959a45034eb06ad3c1d8a76efc0ff478cf390a' 
  AND token = 'r4ogZxhJWfuwnijUcpJFodqQhV1aiQHAKzTsPfF0FF4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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