SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'c66e72083f8044f62ed2a5431363691121cd4b98709b56511c80f5272661e79b' 
  AND token = 'D5635soBMx2M4eLTu1BG865MlQRhg2F5mRAN6efYnPo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00038

JSON explain

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