SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9517e97bb0ed51a68274a2cdc73598cd38ed9be69c4ca18b9384c0687aee1dda' 
  AND token = 'KBJQtu/ZtqVNcnhAkvAPI/wxp6NI0SBewH3zBzZEdMg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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