SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'af43085f8eb2ba2d3e0c5ee4766ced67c7347b6265d5823d486402b8f29f74f1' 
  AND token = 'rQG+DtXVh4ml8tVHFMgNiTMNFEdbEzBdw/JuUxkSHbQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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