SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '300db2c4f94bee275832645bf43d4292a5104e4a7e1f5a313c4a1ebe0809ed47' 
  AND token = 'yeH2LJ/1VCqFBPho8oQVd7AxIGkwRqHTVqJ1b8DWcY0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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