SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '37c43e1fcddb924143d5a7006a053a07912d9de980b3d3615e04b043f01418d9' 
  AND token = 'WzW0rICXP1W1SQRtKjL083l7Rri64ZzB24EHV5uzRXs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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