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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '2e9f22e821cd52fb31c52c7ccce7886b50bda2df45c2af07c441841ff42e0d50' 
  AND token = 't4F7vGpR7BQHhu9DGNld9geGdDD1Z1S+zGd+837iJ14=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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