SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '27c2d97d033b8f93883ae8261a2cf9cc38a8fa65720072bd2447c7f2d8e4fee5' 
  AND token = '/zKsPwxIdxRlyGhzzg6rXV82YjGoxBHf4WkBuyC/row=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00044

JSON explain

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