SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6c7667715fbc87e795a61efaaed162ce714b51af5242ee3ff0319d5a8a6d5607' 
  AND token = 'g/i36Wv5mhdBXOuyLroZ9+vIG+8/Zth224YnflCZXNY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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