SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'd2f418615923951e08bb9c3c2f3eb4040d87f3a81243531482d1ffc05a636502' 
  AND token = 'sAlw5AZDkiJJk/2vyDYII8VCoCzJVBClMpThC6qx4rs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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