SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9cb947f47edd47f99de46cd52431fd9fcd8812ab610ef9d5b42f0834e1acdfaf' 
  AND token = 'fxH7p5AQUhbfNOK5ph81cHlz4jRvKcpK4WJanr4p07A=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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