SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b8e6627af9becc9098c790fcdeb1399e6f41516244258a9a0d22f66fd655c9be' 
  AND token = 'MNyU4Y0xzMuwecQC46GTncA4o/NqboULzZBRYcs7z5Q=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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