SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '044e84f9a86fa769c21301a2ac9657e5baaf91c4b4792feb0d787e4f29ab3c00' 
  AND token = '0BOS/ZWnMX3ggjBFUYfu/CwsXbc8Feu9imYvwckLtzw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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