SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'f3d6b29acc69b323c6b490f853f1a31c44982f4106814034a10b481f9d93be85' 
  AND token = '5Hbmf2CIm/AyGuuz2Hzd+rmmNVqgzdF1G0FJUYj2cZs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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