SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = '402ef60843d8cc9033a1add692cb45278415b7884604bf2975894aa6c7a3bed3' 
  AND token = '0s50E5AvZS6MVB9UzpkdsZ9S44j59yUeN8TTB38p5Sk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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