SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8a27f85fb071aed19937ab26ceb6417c691fdcde8d765b66bc9314951c0c4e57' 
  AND token = 'ZlkUbxP3w7Z34Ryi7OBr+K1VgHGGmG9G3YTSCVoVaAs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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