SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '7ce400ce6374c59b38b290a9d5d2f4ff64af38b668e7f55a88994bfc118ab264' 
  AND token = 'CDczniVWyDHeC0v2PoG1aNvfw0lWInqLyx33dmO//MY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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