SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4cf1293ce074b96ff013621d82fccbd1f59bedf8cf9e7ab75837f7feca1b0f44' 
  AND token = 'CjjrXK9ZW52U8nACq6gDL3I8Jyr+1gwHxfP7Y1AwcOc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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