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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '666d1b1a7264a3828ff1e14e4352376b7066cf88dd1b03a1b4561dffac10cf4e' 
  AND token = '1jJQgG8SVfdp7LyNkUnbvtQlLJ9/IuP1wNpzARlx8g8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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