SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fb5a3b03c2e1d0f14e3ccf7036e77fe568805447c323c193a6f0f39c060b38ad' 
  AND token = 'QLQS6n1+RxiLskNy79P8JKLrWPQInwOWo77Rgy15Oi0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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