SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'aa3863c77dd2c158d02240472e4d21bfb11afc28306dc1252f13ae357018d4a2' 
  AND token = 'RTt26s+vsNzRakOePKp6xLc+D71PKKx9vzhhReQVZ0g=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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