SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '720e3c1baa5b66cec5cacec5f4c66cc2446318a241338014412747cefaefc375' 
  AND token = '6Y7HvfKWPwEwBDwCTic/azMKNUnAXECHchp6tkqbBRs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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