SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '26c1b4be024c9ff3234cbb8231daf5553186e4f406e64ca49f5ab4b7719f06b1' 
  AND token = 'iMTol/5UOnNICZxnEGwUpGrOusMcVbbcM4g3FxQz/Dg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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