SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a81e808479934e61afa9e1f2bf04972089b6cbc1cbe14e12dcdea852c281db9d' 
  AND token = '/yBMCMOimBQqqfdrg5MOEytcXoTRb4Ao6aXZ9Pb7jfA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00051

JSON explain

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