SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '08908ea4daca408f9b0b66499c187a168400733c1014a50e599870a6a16472db' 
  AND token = 'Tz67dGEt9FrVE2FdMqzeXExsMneIEWoZFObifU3OjD8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00052

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}