SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'f7976d846673823b066409c2e80cf2de59c775a1832fbd0acc88190fdabfd142' 
  AND token = 'HVLFIj69sdYc3xw+wphRFQbgNIKt4Yp5undqPaSGFkk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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