SELECT 
  1 
FROM 
  cscart_june_setuplock_keys 
WHERE 
  key_id = '517a0fe30623ac859508e599e0d3fea11d5dec858286ee669fea2033953c3dd7' 
  AND token = 'o1TUqmGGfvMPouzaNys6YnhRvmfdvASVbsh7sPd81cs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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